Next week, NASA is launching its new exoplanet hunter: a satellite that will stare out at the cosmos searching for never-before-seen worlds. Dubbed TESS, the spacecraft is tasked with looking for planets circling around stars outside of our Solar System to help scientists figure out what these planets are made of and if any might be able to support life.

TESS is launching on April 16th, just as NASA’s old exoplanet hunter is about to hang up its hat. The agency’s Kepler spacecraft, which...